Plants don't like touch: Green thumb myth dispelled

December 17, 2018, La Trobe University
Professor Jim Whelan in his laboratory at the La Trobe Institute for Agriculture and Food at AgriBio, Melbourne, Australia. Credit: La Trobe University

La Trobe University-led research has found that plants are extremely sensitive to touch and that repeated touching can significantly retard growth.

The findings, just published in The Plant Journal, could lead to new approaches to optimising plant and productivity—from field-based farming to intensive horticulture production.

Research Director of the La Trobe Institute for Agriculture and Food at AgriBio, Professor Jim Whelan, who led the research, said that even the slightest touch activates a major genetic defense which, if repeated, slows down plant growth.

"The lightest touch from a human, animal, insect, or even touching each other in the wind, triggers a huge gene response in the plant," Professor Whelan said.

"Within 30 minutes of being touched, 10 per cent of the plant's genome is altered.

"This involves a huge expenditure of energy which is taken away from plant growth. If the touching is repeated, then is reduced by up to 30 per cent."

Co-author from La Trobe Dr. Yan Wang said that while we don't yet know why plants react so strongly to touch, the new research findings have led to a deeper understanding of the genetic defence mechanisms involved—opening up new approaches to reducing sensitivity and optimising growth.

"We know that when an insect lands on a plant, genes are activated preparing the plant to defend itself against being eaten," Dr. Yang said. "However, insects are also beneficial, so how do plants distinguish between friend and foe?

"Likewise, when plants grow so close together that they touch one another, the retarded growth defence response may optimise access to sunlight.

"So, for optimal growth, the density of planting can be matched with resource input."

Professor Whelan said with this deeper understanding of the genetic mechanisms involved, it may be possible to identify and breed plant varieties which are less touch sensitive while retaining their sensitivity to other factors such as cold and heat.

The research was carried out using Thale Cress - Arabidopsis thaliana - though it is likely to be applicable to most plants and crops.

Next steps in the research will be to test touch response in crop species and to look at the potential consequences of breeding plants which are less touch sensitive.

"As we don't understand why plants display such a strong defence response to touch, if we are to breed less touch-sensitive varieties, we need to first understand what some of the consequences might be," Professor Whelan said.

"For example, could touch-resistant plants be more susceptible to disease because a crucial defence mechanism has been removed?"

Explore further: Key gene find could enable development of disease-resistant crops

More information: Yue Xu et al, Mitochondrial Function Modulates Touch Signalling in Arabidopsis thaliana, The Plant Journal (2018). DOI: 10.1111/tpj.14183

Related Stories

Hormone keys plant growth or stress tolerance, but not both

January 17, 2018

Plants that grow well tend to be sensitive to heat and drought, and plants that can handle those stresses often have stunted growth. A Purdue University plant scientist has found the switch that creates that antagonism, opening ...

A bit touchy: Plants' insect defenses activated by touch

April 9, 2012

A new study by Rice University scientists reveals that plants can use the sense of touch to fight off fungal infections and insects. The study, which will be published in the April 24 issue of Current Biology, finds that ...

Recommended for you

Semimetals are high conductors

March 18, 2019

Researchers in China and at UC Davis have measured high conductivity in very thin layers of niobium arsenide, a type of material called a Weyl semimetal. The material has about three times the conductivity of copper at room ...

4 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

vaire
5 / 5 (1) Dec 17, 2018
"The research was carried out using Thale Cress - Arabidopsis thaliana - though it is likely to be applicable to most plants and crops." - that is still a bit of an assumption though, isn't it? If nothing else, size and type of plant touched must surely make a difference, too.

Very interesting study, otherwise.

JaxPavan
3.7 / 5 (3) Dec 17, 2018
Perhaps plants just don't like Professor Whelan?
treerap
not rated yet Dec 18, 2018
Maybe it depends who's doing the touching. Dr Alex Shigo was the father of modern arboriculture. He spent a lifetime in the forest analyzing trees - how they grow, interact and respond to their environment. His motto was "touch trees". Having watched him "touch trees" and being a tree hugger myself, I can attest to the fondness that trees have for being respectfully and lovingly touched. They happily share their energy. I think the authors need to get out of their respective laboratories and go into a forest and re-evaluate their conclusions.
Starman Eilat
not rated yet Dec 22, 2018
What is stunting growth mean? are fewer leaves being produced?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.